The present invention is related generally to methods of reinforcing and waterproofing paved surfaces such as roads and parking lots, and more particularly to a method which includes the use of a reinforcement mat.
Paved surfaces such as roads and parking lots are commonly constructed with a top surface layer of asphalt paving material. Over a period of time, the paved surface usually deteriorates due to the effects of traffic, temperature cycles and other environmental causes. Cracks develop in the paved surface, and the cracks can spread and cause further deterioration. Water can penetrate the paved surface by flowing into the cracks, causing further damage.
Damaged paved surfaces are usually repaired by applying a new surface layer of paving material over the damaged portions or over the entire paved surface. After a paved surface having cracks is resurfaced, many times the new surface layer cracks directly over the cracks in the old surface. This is known as xe2x80x9creflective crackingxe2x80x9d. One way to address this problem is to make the new surface layer thicker, but this is not very effective.
Consequently, various reinforcement materials and methods have been tried for preventing or repairing cracks and other deterioration in paved surfaces. One commercial product (an example of which is Petromat(copyright) available from BP Amoco) is a reinforcement mat constructed from polypropylene fibers. The polypropylene mat is applied over a tack coat of asphalt, and then a surface layer of paving material is applied over the mat. The paving material is heated prior to its application over the mat. Unfortunately, the polypropylene mat tends to melt and/or shrink when it is exposed to the hot paving material, which detracts from its ability to provide reinforcement and waterproofing. Additionally, if the tack coat is applied at too high a temperature, the polypropylene mat may likewise shrink or melt.
Another commercial product consists of glass fiber rovings attached to a nonwoven felt. This product and other laminated products are relatively difficult and expensive to manufacture. A laminated product may also experience separation between the layers, which could create a slip plane causing the paved surface to come apart. Also, a cellulosic felt is not as strong as a fibrous mat.
Various patents describe reinforcement materials and methods of reinforcing paved surfaces. For example, U.S. Pat. No. 2,115,667 to Ellis discloses reinforcing an asphalt road with a reinforcing agent made from woven glass. A woven reinforcement material is usually less porous than a nonwoven material. This impedes the ability of the asphalt to penetrate the reinforcement material to create a strong paved surface. A woven material is also usually more expensive to manufacture than a nonwoven material.
U.S. Pat. No. 4,637,946 to Shah et al. discloses a road repair membrane comprising a glass fiber mat impregnated with a blend of asphalt, block copolymer and mineral filler. An impregnated mat would not be very effective in soaking up asphalt to create a strong bond with the road. A weakly bonded mat could delaminate from the asphalt layers, enabling the road surface to come apart.
In view of the above, it would be desirable to provide an improved method of reinforcing and waterproofing a paved surface, including a method of repairing a defect such as a crack in the paved surface.
The above object as well as others not specifically enumerated are achieved by a method of reinforcing and waterproofing a paved surface according to the invention. Initially, a layer of liquefied asphalt is applied on a paved surface. A reinforcement mat is then applied over the liquefied asphalt. The reinforcement mat comprises a nonwoven mat produced from fibers having a melting point above about 320xc2x0 F. (160xc2x0 C.). The fibers are selected from the group consisting of mineral fibers, such as glass fibers; or polymer fibers, and mixtures of mineral and polymer fibers. The liquefied asphalt penetrates and soaks the reinforcement mat to form a water barrier. A layer of paving material is then applied over the reinforcement mat.
In another embodiment of the method, a layer of liquefied asphalt is applied on a paved surface. A reinforcement mat is then applied over the liquefied asphalt. The reinforcement mat comprises a nonwoven mat produced from fibers selected from the group consisting of mineral fibers and a mixture of mineral fibers and polymer fibers. The liquefied asphalt penetrates and soaks the reinforcement mat to form a water barrier. A layer of paving material is then applied over the reinforcement mat.
Another embodiment of the method relates to repairing a crack in a paved surface. A reinforcement mat is applied over the crack by securing the reinforcement mat to the paved surface on one side of the crack, and leaving the reinforcement mat unsecured to the paved surface on the opposite side of the crack. In a preferred embodiment of the repair method, the reinforcement mat comprises a nonwoven mat produced from fibers selected from the group consisting of mineral fibers such as glass fibers; or polymer fibers, and mixtures of mineral and polymer fibers. A layer of paving material is then applied over the reinforcement mat.
Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings.